This invention relates generally to a precast concrete bridge system that is made up of a plurality of sections, and specifically to a concrete bridge system for maximizing a waterway opening while at the same time minimizing the weight of the structure without sacrificing strength.
As described in U.S. Pat. No. 4,564,313, precast structures for use in bridge systems are presently in use which permit safe passage of motor vehicles and the like over waterways, such as culverts, creeks and the like. The bridge is precast in sections wherein each section includes a horizontal deck wall that spans between a pair of vertically disposed legs or side wall supports that are integrally cast with the deck. The sections are placed in a side-by-side relationship upon suitable footings and the completed decking is then paved to complete the structure. The size of each section making up the entire concrete bridge structure is generally limited by the weight of the section that can be safely and legally transported from the casting site to the installation site. As a result of this size limitation, the length of the span that can be achieved by the finished structure is correspondingly limited.
A similar precast bridge is disclosed in U.S. Pat. No. 4,993,872. The precast sections, in this case, contain an arched deck wall having a radius of curvature of between twenty five and forty feet. The arch increases the difficulties involved in lifting, hauling and erecting the sections and results in a loss of waterway openings in the final structure.
It is therefore an object of the present invention to reduce the weight of precast concrete bridge sections without reducing the load carrying capacity of the sections.
A further object of the present invention is to reduce the difficulties associated with lifting, transporting, and erecting precast bridge sections.
A still further object of the present invention is to provide light weight precast bridge sections that can be more easily transported from the casting site to the erection site.
Another object of the present invention is to reduce the cost of precast bridge sections.
Yet another object of the present invention is to provide bridge sections containing voids in the top deck wall and side walls to reduce the dead load weight of the sections while not adversely effecting the load carrying capacity of the sections.
These and other and further objects of the present invention are attained by a concrete bridge system that contains a series of precast sections. Each section includes a planar horizontally disposed deck wall that is integrally joined to a pair of spaced apart vertically disposed legs or side walls. The deck wall and the side walls each contain a plurality of interior cores cast therein that follow the geometry of the containing wall. The cores constitute between 16 to 35 percent of the volume of each wall and are placed so that the load carrying capacity of the structure is not adversely effected. Reinforcing rods are placed between the voids and the opposed outer surfaces of each wall to further enhance the strength and load carrying capacity of the structure.